The glaziers of Yugoslavia are everywhere, replacing windows broken in last week's "revolution" that brought President Vojislav Kostunica to power.

But as trucks laden with plate glass offload at the steps of the burned-out parliament building, and store owners fit new panes, tensions are building over the renewed influence of ousted strongman Slobodan Milosevic and his allies, which could lead to violence - and more broken glass.

The pro-democracy movement has given Milosevic cronies until today to agree to new elections in the Serbian parliament - a preliminary agreement earlier this week was abruptly rescinded - or face renewed street protests. There were signs yesterday that a deal might be struck, but many Serbs were anxious about the next steps. Milosevic allies still controlled the police force.

"No doubt Milosevic is pulling the strings. They want to slow down people's anger and momentum," says Bratislav Grubacic, editor of the VIP newsletter in Belgrade. "The sense of revenge is great, and if people go back on the street again, there could be a slaughter."

From his well-protected home in a Belgrade suburb, Mr. Milosevic reportedly is meeting with a stream of backers, energizing supporters in a way that appeared impossible just days ago, when hundreds of thousands of protesters took to the streets to force Milosevic to accept defeat in Sept. 24 elections.

The result is a power struggle that on Wednesday saw the powerful parliament of Serbia, Yugoslavia's dominant republic, declare it would halt cooperation with Mr. Kostunica's transition team. Both the Yugoslav and Serbian parliaments are controlled by Milosevic's party and its allies. Senior generals also warned against the "negative consequences" of top-rank purges planned by the new leadership.

Also a problem for Kostunica are emerging differences in his 18-member coalition, and policy freelancing by some members. Pro-Milosevic managers are being pushed out of factories, mines, and hotels by angry staff in dramatic confrontations across the country. Milosevic's Socialist Party accuses the new leaders of bringing "lawlessness and violence" to Serbia.

"I cannot justify all that's going on," Kostunica said in an interview with The New York Times. "On the surface there is a peaceful, democratic transition, but below the surface is a kind of volcano, not so controlled."

"I am having almost as much trouble from my friends as from my enemies," he added, in executing the transfer of power.

One senior pro-democracy leader, Zoran Djindjic, warned on Wednesday that if the Serbian parliament didn't agree to new elections by today, then "we will call the people to the streets to demand new elections." He said the Serbian parliament - which was not up for election in the federal vote that brought Kostunica to power - was overplaying its hand: "It's a fact of life they have no control over 80 percent of the processes in the country."

On Thursday, however, he reported that a crisis might be averted: "I think we have an agreement that it should be done in a political way, through elections and through some kind of cooperation to keep the country stable without economic or energy crisis."

Part of the problem, Serb analysts say, is that Kostunica's legal insistence on doing the transfer of power "right" is being taken advantage of by more ruthless adversaries.

"Kostunica is underestimating what could happen still. He is a very nice person, and very legally inclined, so maybe he can't understand what crooks they are," says Mr. Bratacic. "Milosevic can't reverse the process and retake power, but he can cause trouble. We are dealing with people [who] are not willing to give up power, and if a civil war results [in their view], so be it.

"With this behavior, [Milosevic] will really force people to kill him. People will say, 'We must hit the snake in the head,'" he adds. "Kostunica must now become a mature politician, or he will be lost."

Pro-Milosevic forces appeared to be consolidating what remained of their grip on power. The Socialist Party announced the replacement of its hard-line chief Gorica Gajevic with the more moderate Zoran Andjelkovic, who now heads a Serb-run Kosovo government.

On top of domestic problems, Kostunica has been swamped with European and American visitors, and shows of support from around the world. President Clinton yesterday lifted an oil embargo and flight ban against Serbia, echoing moves earlier this week by the European Union. In a written statement, Mr. Clinton said the US has "a strong interest in supporting Yugoslavia's newly elected leaders as they work to build a truly democratic society." US diplomat William Dale Montgomery arrived in Belgrade Wednesday, and more senior officials are expected soon.

But the burden of leadership seemed a heavy load for Kostunica, whose appeal to voters has been in part because he had no political background. "It is true he is inexperienced," says Aleksa Djilas, a historian and public-policy scholar currently at the Woodrow Wilson Center in Washington. "He is also a decent person who believes in the rule of law. His advantage is that a lot of people voted for him. And the fact that he has not behaved like a revolutionary could be helpful in the long run."